Hybrid supercapacitors, which combine the advantages of supercapacitors and rechargeable batteries, have the potential to meet the demands of both high-energy and -power in electrochemical energy storage systems. However, the energy density of the hybrid supercapacitors has been limited because of the low capacity of the activated carbon cathode. Here we introduce a high-capacity carbon cathode containing plenty of oxygen functional groups that are redox-active towards both Li- and Na-ions. This functional carbon has an ultra-thin two-dimensional structure that has significant advantages in utilizing the redox reactions. The functional carbon cathode can exhibit very high capacities of ∼250 mA h g-1 in Li-cells and ∼210 mA h g-1 in Na-cells. A hybrid supercapacitor consisting of the two-dimensional functional carbon cathode with a commercial level loading density of ∼9.3 mg cm-2 and a Si-based anode delivers a high-energy density of ∼182 W h kg-1 at a high-power density of 1 kW kg-1.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)